MILK PRODUCTION IN CATTALO COWS AND ITS INFLUENCE ON CALF GAINS
Milk yield in 91 lactations from cattalo cows averaging about 14% bison–86% Hereford was estimated by five milkings during 185-day intervals in each of the years 1961–1963 at the Agriculture Canada Experimental Farm, Manyberries, Alberta. Estimated 24-h milk yield was highest in June (6.36 ± 0.17 kg) and lowest near the termination of lactation in October (3.16 ± 0.08 kg). Total estimated milk yield (TMY) from parturition to the end of the 185-day lactation period was 938 ± 22 kg. Age of dam was a major source of variation in TMY and TMY decreased by 10.8 ± 5.3 kg for each percent increase in bison percentage of dam (B % dam). Gain from birth to 185 days of age (TGAIN) of cattalo calves was highly correlated with TMY (r = 0.79) and periodic milk yields throughout the lactation period (r = 0.59–0.76), with TGAIN being greatest in calves from older dams (5–9 yr). Correlations of mean percent fat (%F), protein (%P), and solids-not-fat (%SNF) in the milk from cattalo dams with calf TGAIN were generally low and inconclusive due to small sampling numbers. Although milk yield decreased through the lactation period, %F, %P, and %SNF in the milk increased proportionally. B-% dam did not influence average daily gain between milkings or TGAIN of calves to any appreciable extent. TMY accounted for 75% of the known variation in TGAIN and calves were found to be 0.057 ± 0.005 kg heavier at 185 days of age for each 1-kg increase in TMY.